This project is concerned with the development of statistical/mathematical methodology useful in the assessment of human health risks associated with exposures to potentially hazardous environmental agents. The primary focus in on the generation of improved statistical techniques for estimating adverse human health effects from laboratory animal data; and special emphasis is placed on dose-response modeling, low-dose extrapolation and species scale-up. Consideration is also given, on occasion, to the analysis and modeling of laboratory data for occupational/environmental agents of special interest. Present research efforts are particularly concerned with the impact of pharmacokinetic considerations on dose-response modeling in carcinogenesis and with the determination of the most appropriate dosage scale (and the examination of other related issues) for species extrapolation in teratology.